U.S. Pat. No. 4,370,532 teaches the use of a removable key cap with locking detent, and a flanged light pipe to transmit illumination through the opaque key cap.
U.S. Pat. No. 4,002,873 teaches a push button switch telescopically mounted on a switch base with a plurality of outwardly extending arms positioned between the button and the base. Some of these arms receive the actuating force of the button, while others provide contact with terminals in the base. Light is transmitted from an illuminating means in the base through an opening in the contact towards a light transmissive portion of the button.
U.S. Pat. No. 4,354,077 teaches use of the outer shell as the main structural member wherein front relamping and a sealed snap disk are employed.
U.S. Pat. No. 3,989,912 teaches bending back lamp leads to contact terminals in the lamp base.
U.S. Pat. No. 4,346,275 teaches the use of guide legs to secure the frame to the holder for securement, and the use of a removable transparent cap.
U.S. Pat. No. 4,385,219 teaches the mounting of the lamp independent of the movement of the push button switch by routing the lamp leads through slots in the plunger and along channels in the upper and lower housing to contact the lamp leads directly to the printed circuit board. This configuration does not allow removal or replacement of the lamp without first unsoldering or breaking the lamp leads.